fix(printer): distinguish between Ppat_constraint / value_binding

CHANGES.md

@@ -9,7 +9,9 @@
 - printer: pad record braces with spaces (@anmonteiro,
   [#2859](https://github.com/reasonml/reason/pull/2859))
 - printer: don't escape infix keywords (@syaiful6,
-  [#2872](https://github.com/reasonml/reason/pull/2859))
+  [#2872](https://github.com/reasonml/reason/pull/2874))
+- fix(printer): wrap `Ppat_constraint` in parentheses (@anmonteiro,
+  [#2874](https://github.com/reasonml/reason/pull/2874))
 
 ## 3.16.0
 

src/reason-parser/reason_pprint_ast.ml

@@ -5571,17 +5571,24 @@ let createFormatter () =
            sixteenTuple = echoTuple ( * 0, * 0, * 0 * ); *)
 
         method formatSimplePatternBinding
+          ?(wrap=false)
           labelOpener
           layoutPattern
           typeConstraint
           appTerms =
           let letPattern =
+            let layoutPattern =
+              match typeConstraint, wrap with
+              | (Some (_, `Constraint), true) -> makeList ~wrap:("(","") [layoutPattern]
+              | (Some _ | None), _ -> layoutPattern
+            in
             label ~break:`Never ~space:true (atom labelOpener) layoutPattern
           in
           let upUntilEqual =
             match typeConstraint with
             | None -> letPattern
-            | Some (tc, `Constraint) -> formatTypeConstraint letPattern tc
+            | Some (tc, `Constraint) ->
+              makeList ~wrap:(("", if wrap then ")" else "")) [ formatTypeConstraint letPattern tc ]
             | Some (tc, `Coercion ground) -> formatCoerce letPattern ground tc
           in
           let includingEqual =
@@ -6223,6 +6230,7 @@ let createFormatter () =
                 in
                 let appTerms = self#unparseExprApplicationItems expr in
                 self#formatSimplePatternBinding
+                  ~wrap:true
                   prefixText
                   layoutPattern
                   typeLayout

test/4.10/attributes-re.t/run.t

@@ -774,7 +774,7 @@ Print the formatted file
     )
     This will get sugared to `let ([@attr] x2) : int = xInt`
   */
-  let ([@attr] x2): int = xInt;
+  let (([@attr] x2): int) = xInt;
   /**
     Attribute on the pattern holding the constraint:
     pattern(

test/4.12/attributes-re.t/run.t

@@ -774,7 +774,7 @@ Print the formatted file
     )
     This will get sugared to `let ([@attr] x2) : int = xInt`
   */
-  let ([@attr] x2): int = xInt;
+  let (([@attr] x2): int) = xInt;
   /**
     Attribute on the pattern holding the constraint:
     pattern(

test/basicStructures.t/run.t

@@ -330,8 +330,8 @@ Format basicStructures
    */;
   let x: int = 10;
   let x: int = 10;
-  let x: int = 10;
-  let x: int = (10: int);
+  let (x: int) = 10;
+  let (x: int) = (10: int);
   /* let (x:int) = (10:string); */
   /* let (x:string) = ("hello":int); */
 
@@ -341,7 +341,7 @@ Format basicStructures
 
   /* In Reason, types look like the data they model! Tuples are no exception. */
   type pairOfInts = (int, int);
-  let letBindingWithTypeConstraint: int = 10;
+  let (letBindingWithTypeConstraint: int) = 10;
   let (tupleItem: int, withTypeConstraint: int) = (
     10,
     20,

test/general-syntax-re.t/run.t

@@ -643,7 +643,7 @@ Format general implementation syntax
   /* We could even force that consistency with let bindings - it's allowed
         currently but not forced.
      */
-  let myAnnotatedValBinding: int = 10;
+  let (myAnnotatedValBinding: int) = 10;
 
   /* Class functions (constructors) and methods are unified in the same way */
 

test/patternMatching.t/run.t

@@ -290,8 +290,8 @@ Print the formatted file
   type aOrB =
     | A(int)
     | B(int);
-  let (nestedAnnotation: int): int = 0;
-  let (A(i) | B(i)): aOrB = A(0);
+  let ((nestedAnnotation: int): int) = 0;
+  let ((A(i) | B(i)): aOrB) = A(0);
 
   type test_foo =
     | VariantType1

test/wrapping-re.t/run.t

@@ -2217,12 +2217,12 @@ Format wrapping in .re files
     someVar3,
   );
 
-  let theTupleTypeAnnotationShouldWrap: (
+  let (theTupleTypeAnnotationShouldWrap: (
     string,
     string,
     string,
     string,
-  ) = (
+  )) = (
     "now these tuple values should wrap",
     "now these tuple values should wrap",
     "now these tuple values should wrap",